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https://issues.apache.org/jira/browse/NET-550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14089627#comment-14089627
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Bernd Eckenfels commented on NET-550:
-------------------------------------
Hm, I was looking at the usage of this in VFS, because it is affected: it does
not set an explicite buffer size.
When I drill down into the 3.3 code, it looks like it correctly generated
getBufferedXXXStream() for __bufferSize==0 (using default buffer size of 8k
from Java bufferedxxxStream). However besides the buffered streams it also uses
the buffer size for the copy loop. And in this case it does not use a default
buffer. Which is quite strange because I wonder why read[byte[0]) works anywy.
It only works because it has a read() fallback, which is clearly not the
intention of the code.
Attached is a proposed minimal fix, but instead of that the buffering should be
reconsidered completely.
> Default FTPClient bufferSize results in very slow retrieve transfers
> --------------------------------------------------------------------
>
> Key: NET-550
> URL: https://issues.apache.org/jira/browse/NET-550
> Project: Commons Net
> Issue Type: Bug
> Affects Versions: 3.3
> Reporter: Geoffrey Hardy
>
> While experimenting with FTPClient, I discovered that if I don't call
> setBufferSize(), the default value is zero. This results in retrieveFile()
> calling the version of InputStream.read() with no parameters, reading one
> byte at a time. For comparison, the downloading a CD ISO image of about
> ~648MB took 18m10s with the default settings. In contrast, calling
> setBufferSize(8192) took only 7.9s, an improvement of ~137x.
> Here is some sample code:
> {code:java}
> FTPClient ftp = new FTPClient();
> // ftp.setBufferSize(8192);
> ftp.setControlKeepAliveTimeout(300);
> ftp.setCopyStreamListener(new CopyStreamListener() {
> @Override
> public void bytesTransferred(long totalBytesTransferred, int
> bytesTransferred, long streamSize) {
> System.out.println("totalBytesTransferred: " + totalBytesTransferred
> + ", bytesTransferred: " + bytesTransferred + ", streamSize: " +
> streamSize);
> }
> @Override public void bytesTransferred(CopyStreamEvent event) {}
> });
> ftp.connect(host);
> ftp.login(user, pass);
> ftp.retrieveFile(file, outputStream);
> {code}
> The log message from the stream listener printed lots messages
> "bytesTransferred: 1" and totalBytesTransferred incremented by 1 each time.
> This corresponds to the part of the code which reads one byte at a time with
> {{int inputStream.read()}}.
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